(a) Field of the Invention
The present invention relates to a projector-type head lamp assembly for use with vehicles.
(b) Description of the Prior Art
The essential requirements for the head lamp for a vehicle or car are to provide a bright view in front of the car and to provide a luminous intensity distribution pattern owing to which the driver of a car running in the opposite direction is not dazzled by the coming light beam.
As a head lamp which has a luminous intensity distribution pattern meeting these requirements, of which the lens configuration is simple and which can project light rays to a relatively far range in front of the car, the so-called projector-type head lamps have been proposed. Such a projector-type head lamp comprises a reflector of which the reflection surface is composed of a spheroidal surface or a paraboloidal surface, or a combination of them, a shade disposed in front of the reflector and which blocks a part of the light rays reflected by the reflector to define a light-dark boundary, and an image forming optical system disposed in front of the shade. In such projector-type head lamp, the reflection surface is generally formed by a spheroidal surface or a paraboloidal surface, or a combination of them and a major consideration is given to provide an ample illumination over a long distance in front of the car.
However, in a relatively near range in front of the car, the light beam does not spread so widely horizontally that it is sometimes difficult for the driver to visually check a person walking on the sidewalk within the range or a car approaching an intersection also within range. Namely, the conventional head lamps involves a problem not preferable for the traffic safety.
Also, in case of a projector-type head lamp in which the lamp bulb filament is disposed in the direction of the optical axis, the luminous intensity on the road surface in the relatively near range in front of the car is high while the luminous intensity in the far range is extremely low as compared with that in the near range, so that an object in the far range cannot be easily viewed.